Manhole installation and repair assembly

ABSTRACT

A manhole installation and repair assembly. The assembly has a first load carrying member and a second load carrying member. Each load carrying member has a midspan seat arranged substantially at a midspan location of the respective load carrying member&#39;s. The midspan seats form a crossmember joint, the joint enables the load carrying member&#39;s to be arranged in the same plane and also provides for structural continuity between the load carrying members. The load carrying member&#39;s each have ground engaging locations and manhole ring retainer elements to grab on to the manhole ring holding the ring and cover in suspension below the load carrying members. An inflatable form liner is used to span the gap between the manhole ring and the top of the manhole cone.

RELATED APPLICATIONS

This application claims priority benefit of U.S. Ser. No. 60/805,558, filed Jun. 23, 2006.

BACKGROUND

US patent application 2004/0109727, published Jun. 10, 2004, discloses a method and device for adjusting the height of a manhole. The height adjusting member has a tubular shaped frame which is installed into the ground and removable height adjusting members on the tubular shaped frame which enable the cover received on the frame to be raised and lowered. In the object of the invention section on page 1 paragraph 16, “this invention was made to improve a conventional manhole. This invention is to provide a safe, efficient and improved manhole which offers a flexible height adjusting mechanism with the ability to add or remove height adjustment members at any height and a method for adjusting the manhole height . . . .”

U.S. Pat. No. 6,869,249 discloses an adjusting device for installing a manhole ring onto a manhole. The device has a center plate and at least one supporting arm. Each supporting arm has a first end and a second end with the supporting arm secured to the center plate. An assembly associated with the center plate holds the manhole ring. As seen in column 2 around line 47, “the adjusting device of the present invention includes a first supporting arm, a second supporting arm and a third supporting arm, with each arm having a first end and a second end.” Furthermore, still in column 2 around line 66, “it is within the scope of the present invention to have more than three supporting arms or less than three supporting arms depending on the desire of the manufacturer.” Furthermore, in column 3 at line 26, “the first supporting arm includes a first leg having a first end and a second end. The first leg is secured to the first supporting arm at a 90 degree angle”.

As discussed in col. 3 around line 67, “the present invention further includes a manhole ring securement assembly.” The assembly includes a first, second, and third extension member each attached to the first, second, and third supporting arms.

U.S. Pat. No. 6,371,687 discloses a method and apparatus for leveling a manhole cover frame. The method and apparatus uses a leveling clip which attaches by friction to the external peripheral flange of the manhole cover frame. As seen in col. 2 around line 4, “this invention comprises a clip that fastens to the outer flange on a manhole cover frame. The clip is threaded to allow a leveling boot to raise or lower the manhole cover frame with respect to the topmost manhole precast riser ring, allowing for the perfect alignment of the manhole cover frame with the roadway surface. The individual clips may be positioned anywhere along the peripheral flange of the cover frame in accordance with the contour of the roadway surface.”

U.S. Pat. No. 6,161,985 discloses a manhole collar assembly, which includes raising a manhole ring during construction or repair of roads. Referring to col. 2 around line 26 in the Summary of the Invention section, “the instant invention comprises a forming system to create a concrete collar around the access opening for underground utility maintenance. The forming system comprises a prefabricated form, and a trimming assembly for on-site custom trimming of the form to the proper height and orientation, for accurate placement of the manhole ring to be level with paved road surface.” Further down in col. 2 around line 39, “the invented system particular from the subterranean utility area that is to be accessed.”

U.S. Pat. No. 5,492,656 discloses an apparatus and method for manhole collar construction, where the manhole collar is constructed between an existing manhole cone and a precast manhole ring. In the Summary of the Invention section in col. 1 around line 52, “the apparatus includes a slip form tube, tapered from top to bottom, and circular cross-section, for insertion into a manhole cone; a plurality of arms radially and perpendicularly extending from the slip form tube for supporting the apparatus on the surrounding road surface; and fasteners for attaching a precast manhole ring about the periphery of the slip form tube for holding the ring at a precise height for the pouring of concrete to form a collar between the manhole cone and the ring.” As seen in col. 2 around line 62, “at least two support arms for supporting the slip form tube upon a support surface are fixed . . . preferably, apparatus includes four arms, equidistantly spaced and radially extending outward from the slip form tube; each arm being provided on its upper surface, adjacent to the end of the arm with a handle so that two workers, standing on opposing sides of the slip form tube, may each grasp two of the handles on adjacent arms.” Furthermore in col. 3 around line 10, “each arm is mounted to slip form tube by means of a pair of laterally spaced angle brackets and a pivot pin for pivoting the arm downwardly adjacent to the wall of the slip form tube for convenient transportation and storage.”

U.S. Pat. No. 5,328,294 discloses a manhole casting setting fixture, which includes a pair of parallel spaced frame rails connected together by a plurality of struts. In the Summary of the Invention section in col. 2 around line 19, “Four loop handles are secured at the opposite ends of the frame rails to facilitate manual manipulation and transportation of the fixture. A pair of clamp mounting blocks are positioned in juxtaposed relation centrally on bottom surfaces of the frame rails. A pair of lead screws extending through respective threaded coaxial bores in the mounting blocks and include handle portions to facilitate manual loosening and tightening of the lead screws. A pair of arcuate clamping jaws are rotatably mounted on oppositely directed end portions of the lead screws.”

U.S. Pat. No. 3,847,339 discloses an apparatus for installing manhole rings. The apparatus includes an elongated rectangular frame which is supported on top of the roadway pavement extending over an opening which includes the manhole. The frame has a plurality of J-hooks which support the manhole ring coaxially above the support shoulder of the manhole. A collapsible drum shaped overlapping shield is expanded by a toggle mechanism into tight engagement with the inside wall of the manhole ring and the subjacent inner margin of the support shoulder, allowing a mold around which concrete is poured and allowed to set.

U.S. Pat. No. 3,219,308 discloses a form locator and, as seen in column 2 around line 1, enables concrete piers constructed with flexible round tubular forms to be accurately positioned, to have their tops level and at the proper elevation when poured. Further down in column 1 at line 37, the form locator is basically a square metal plate with a hole in the center only slightly smaller than the tubular form over which it fits. Surrounding the hole on the underside of the form locator is a positioning ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section detail view of the assembly;

FIG. 1A is a perspective detail view of the assembly;

FIG. 2 is a cross-sectional detail view of the assembly at midspan;

FIG. 3 is a cross-sectional detail view of an alternative embodiment of the assembly at midspan;

FIG. 4 is a cross-sectional detail view of an alternative embodiment of the assembly at midspan;

FIG. 5 is a cross-sectional detail view of an alternative embodiment of the assembly at midspan;

FIG. 6 is a cross-sectional detail view of an alternative embodiment of the assembly at midspan;

FIG. 7 is a perspective view of an alternative embodiment of the inflatable form liner in an uninstalled position;

FIG. 8 is a perspective view of an alternative embodiment of the inflatable form liner in an installed position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The general concept is to provide a set of utility manhole installation formwork assembly which provides an efficient installation process to fix or install the top rim and manhole cover for utility and storm water sewer manholes and inlets. The concept aids in the alignment of the manhole cover with the existing and/or proposed slope of the roadway. The contractor has a higher level of confidence that the top portion of the manhole is being installed in line with the proposed roadway longitudinal and cross transverse roadway slope or grade. This proper installation with the roadway slope mitigates wear and tear on the manholes as they are subjected to traffic and provides for a longer lifespan of the manhole cover reducing municipal replacement costs.

Referring to FIG. 1, a discussion of the utility formwork apparatus 10 will be provided followed by a discussion of the method of installation.

The discussed embodiment materials and arrangement are just one embodiment of the concept and should in no way limit the overall scope of coverage of the claims as directed to the embodiments. For example, in lieu of aluminum, steel, composite carbon, wood, or other material which has the structural properties to support the functionality of the assembly as it repairs or installs the manhole cover can easily be provided.

Furthermore, the cross-sectional properties of the arms can either be rectangular, circular, or square, either a hollow tube or solid material throughout, and may be a combination of all the above as long as the functionality and strength-carrying characteristics of the arms are not compromised.

The utility formwork apparatus 10 has two main cross-section elements. The first element is a longitudinal aluminum arm 12 which in the present embodiment is a ¾ inch by 3 inch aluminum bar. At either end of the longitudinal aluminum arm 12 are handles 14 which may be extended in the longitudinal direction of each arm.

In the transverse direction, a nearly identical transversely aligned aluminum arm 15 is provided with a nearly continuous cross-section 19 at the mid-span where the two arms cross over one another while holding the manhole cover and iron rim 24 to be either repaired or installed.

The first longitudinal arm 12 has in this particular embodiment, a consistently rectilinear cross-section until it reaches the mid-span where a mid-span notch 21 has a seat for the transverse arm to fit. When the transverse arm 15 is seated within the mid-span notch 21, and the two arms are attached to one another, the entire utility form work assembly 10 can carry the iron rim and manhole cover in a suspended insulation/repair state. Furthermore, the longitudinal arm 12 and the transverse arm 15 are both arranged within the horizontal plane defined by the longitudinally transverse axis. Because both the longitudinal arm 12 and the transverse arm 15 can extend across the entire excavated region 46 (FIG. 1), proper alignment is achieved with the cover plate of the manhole more accurately aligned with the top surface of the roadway 28. The transverse arm 15 transfers the compressive capacity load within the compression zone of the longitudinal arm 12 at the mid-span location where the moment is the greatest.

In the present embodiment, while the notch is arranged in a substantially rectilinear cross-section, other configurations are easily conceived especially considering the varying configurations of the cross-section of the arms 12 and 15. For example, the longitudinal arm 12 may be a structural tube-type number either in a cross-sectional cylindrical shape or in a rectilinear structural tube shape. The longitudinal arm 12 can have a circular opening at the mid-span location, the circular opening acting as the mid-span notch 21, the circular opening receiving the appropriately sized transverse arm 15 which can be slidably inserted through the opening 21.

As can be seen in FIG. 1, the aluminum arms 12 and 15 span across an excavated portion 21 of the asphalt 28. The excavated portion has been provided so that access to the top edge 41 of the existing or new precast reinforced concrete manhole cone 40 can be provided. The utility formwork apparatus 10 has on both the longitudinal and transverse bar sliding retainer sleeves 16 which have top screws 18 and side set screws 20. These set screws enable the contractor to adjust the sliding retainer sleeves 16 into an engagement position with the outer face of the iron rim 24 of the manhole cover.

A discussion of the various embodiments of the midspan crossing section of the longitudinal 12 and transverse 15 arms will be provided.

Referring to FIG. 2, a midspan notch with rectilinear arms 98 is provided where the transverse arm 15 is in a rectilinear configuration along with the longitudinal arm 12. Here a rectilinear notch 19 is placed within the midspan location of the longitudinal arm, and effectively removes the top half or so of the material area of the longitudinal arm to make room for the transverse arm 15 to be seated. Similarly, the transverse arm has a notch in the bottom half of its cross-sectional area to seat within the longitudinal arms upper notch half. The cross-sectional body of the transverse arm 15 of the upper portion of the transverse arm acts as the material to transfer the compression forces 100 which occur at the midspan of the longitudinal arm 12. Also, at the bottom area of the longitudinal and transverse arms as the tension zone since the longitudinal arm 12 has a continuous material cross-section the tension forces are transferred along the bottom half of the longitudinal arm. On the bottom half of the transverse arm, the tension forces are not transferred because of the lower seated gap. Therefore, a tension plate 106 is provided to connect the bottom fibers of the transverse arm and the tension zone 102. Two bolts are provided at either end of the tension plate 106 to transfer the tension forces into the transverse arm.

In the above configuration, as seen in FIG. 2, both the longitudinal arm 12 and the transverse arm 15 are maintained within the same horizontal plane thus providing for accurate alignment of the iron rim and cover plate with the profile of the roadway.

An additional alternative embodiment as seen in FIG. 3, the longitudinal arm 12 is set lower than the transverse arm 15. A seat differential 116 must be made up through ground engaging stands at the ends of the transverse arm 15. The seat differential is the distance between the seat elevation of the transverse arm as it sits in the midspan notch 19 of the longitudinal arm 12 and the bottom cord of the longitudinal arm. Because the transverse arm 15 does not have a notch in the bottom portion of the cross-section, a tension plate 106 is not required. In this particular embodiment, the longitudinal arm 15 is secured to the transverse arm through the use of arm connection clip angles 118, which have been welded onto the transverse arm and in this particular embodiment can be bolted to the longitudinal arm.

While it may be advantageous to maintain each of the arms in the same horizontal plane to provide the same elevation as well as the same strength carrying characteristics, the arms may be of different proportionate sizes with the smaller arm or larger arm providing the majority of the weight carrying capacity depending on the connection.

Referring to FIG. 4, the arms are provided in a circumferential tube steel configuration 120 with the midspan notch 19 acting as a circular through hole in the larger longitudinal arm having the greater diameter 12. The transverse arm in this particular embodiment has a smaller diameter and can be threaded through the circular notch 19. Ground engaging seats at either end of the transverse arm make up for the seat differential 116. A set screw 122 can be turned to clamp the transverse arm into place with the longitudinal arm.

An alternative embodiment of the arm carrying members is provided as seen in FIG. 5. Here the arms are constructed as previously seen in FIG. 4 of circumferential tube steel. The arms in this particular embodiment are of the same outer diameter 138. Here the longitudinal arm 12 has an upper notch 19 while the transverse arm 15 has a lower notch. To transfer the compression forces in the longitudinal arm, a compression transfer clamping plate 132 is provided. The clamping plate has an inner radius which matches the outer diameter 138 of the tube steel pipe. Furthermore, the clamping plate in the compression zone has two threaded bolts which secure the clamping plate 132 to the top edge of the longitudinal arm 12. On the bottom surface of the transverse arm 15, a bottom tension transfer plate 134 is provided to transfer the tension forces across the bottom notch of the transverse arm at the midspan. Two equal but opposite set screws connect the bottom tension transfer plate 134 to the bottom surface of the transverse arm 15.

A further alternative embodiment as seen in FIG. 6 is a rectilinear tube steel arm configuration 150 with midspan notches to maintain the tube steel arms within the same horizontal plane. The configuration is similar to that as seen in FIG. 2 with the main difference being the tube steel members have a hollow inner region whereas the longitudinal and transverse arms of the embodiment as seen in FIG. 2 are solid aluminum members. Again a tension transfer plate 152 is provided at the bottom fiber of the longitudinal rectilinear tube steel arm 12, while another connection plate is needed at the top to transfer the compression zone because the rectilinear members seat adequately within one another to transfer the compression forces between the top fibers of the longitudinal and transverse arms.

Discussion of the installation of the iron rim and manhole cover over an existing or new precast concrete manhole cone utilizing the installation and repair assembly will now be provided. Referring back to FIGS. 1 and 1A, the manhole cover is placed in its position on the iron rim 24 and the sliding retainer sleeves 16 are tightened about the rim 24. The entire utility formwork apparatus 10 is then moved from a staging location to its position above the opening of the manhole cone 40. Because there is a vertical gap between the bottom face of the iron rim 24 and the top edge 41 of the manhole cone 40, formwork is needed to provide a temporary wall to seal off the concrete aggregate mix with super plasticizer 48 which is to be poured into the excavated region 46 of the area surrounding the top edge of the manhole cone 40. In order to provide an adequate sealing wall, an adjustable form liner 32 is provided on the inside face of the iron rim 24 extending down into the top portion of the manhole cone 40. An inflatable form liner bladder 30 is provided on the inside portion of the adjustable form liner 32 to provide for lateral stability and keep the wet aggregate mix 48 from pressing into the form liner and dropping down into the manhole barrel 42.

In an alternative embodiment, the inflatable form liner bladder 30 is arranged such that when inflated, it can act as the form liner itself to seal the vertical 35 prior to pouring of the concrete aggregate to fill in the excavation 46 and concurrently set the manhole iron rim 24 into place.

The inflatable form liner bladder 30 in the alternative embodiment when it is used solely as the form liner, in one arrangements is provided as seen in FIGS. 7 and 8, is a flat tube inflatable form liner configuration 180. In this particular embodiment, the inflatable tube has a generally rectilinear cross sectional shape but with a tapered front end 186 and a tapered back end 188. In its uninstalled state, the inflatable form liner 180 stands as a rectilinear wall, with the sidewalls 191 acting as the inner and outer walls of the form liner itself. The form liner when it is installed on the inside face of the iron rim 24 as seen in FIGS. 1 and 1A, laps the tapered ends 186 and 188 respectively, and enables the coiled and inflated form liner to exert an uncoiling force 202 against the inner walls of the iron rim 24 and the manhole cone 40. The uncoiling force helps maintain the form liner in position. The liner wall height 190 is tall enough to fill the vertical gap distance 35 as well as provide overlap with the iron rim with an overlap iron rim distance 208 as well as an overlap cone distance 206 for the precast cone 40. The outer wall surface 204 of the inflatable form liner acts as a mud engagement side where the aggregate mix 48 bears up against the outer wall surface 204 of the form liner. The outer wall surface 204 in one embodiment may have a thicker wall lining to resist puncture from materials within the aggregate such as miscellaneous nails, sharp edges from rocks etc.

Optional reinforcing 34 is extended from the top edge of the manhole cone 40 into the aggregate mix 48 for a more complete connection between the manhole cone and the manhole cover itself.

Once the adjustable form liner 32 has been positioned adequately through the lateral inflatable form liner bladder 30, the concrete aggregate mix 48 is placed inside of the excavated portion 46 of the area about the top edge of the manhole cone 40. Approximately 2 inches of vertical gap is left between the top edge of the aggregate 48 and the top vertical edge of the asphalt 28. Asphalt after the utility formwork apparatus has been removed from the now cast in place iron rim 24 and the manhole cover can be provided.

Therefore further discussing the method of utilizing the utility formwork apparatus 10 and replacing for example a defective or damaged manhole cover would be first to excavate around the existing concrete manhole cone 40 grading and excavation 46, remove the ring and the cover from the top of the manhole cone 40. The next step would be then to position the ring and cover within the utility formwork assembly 10. After doing so, the next step includes installing the adjustable form liner 32 and the inflatable form liner bladder 30 or in the alternative, the inflatable form liner 180, for installation within the existing manhole cone opening 40. The contractors then set the assembly 10 over the manhole. The inflatable bladder is then inflated by the contractors to seal the inside wall of the formwork. The concrete or mud is then poured by the contractors. The concrete then cures, the assembly 10 is then removed and the asphalt is installed.

While the present invention is illustrated by description of several embodiments and while the illustrative embodiments are described in detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the scope of the appended claims will readily appear to those sufficed in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general concept. 

1. A midspan cross member joint for a manhole installation assembly, said joint comprising: a. a first midspan seat arranged substantially at a first mid-span location of a first load-carrying member; b. a second midspan seat arranged substantially at a second mid-span location of a second load-carrying member; c. said first midspan seat arranged to receive said second midspan seat and form said cross member joint; d. said cross member joint enabling said first load caring member and said second load carrying member to be arranged within a first horizontal plane; e. said crossmember joint maintaining a structural capacity to hold a load maintained by said first and second load-carrying members.
 2. The joint according to claim 1 wherein said joint further comprises: said first load-carrying member and said second-carrying member resisting a maximum midspan moment provided by said carried load and applied at the crossmember joint.
 3. The joint according to claim 1 wherein said joint further comprises: a. said first load-carrying member comprising a first top cross sectional compression zone, said first top cross sectional compression zone interrupted by said first midspan seat; b. said second load carrying member comprising a second bottom cross sectional tension zone, said second bottom cross sectional tension zone interrupted by said second midspan seat; c. said second midspan seat of said second load-carrying member further comprising a second top compression zone to transfer a first compression force in said first load-carrying member across said first midspan seat; d. said first midspan seat of said first load carrying member further comprising a first bottom tension zone to transfer a second tension force in said second load carrying member across said second midspan seat.
 4. The joint according to claim 3 wherein said first bottom tension zone further comprises: a. a first cross-sectional area of said first load carrying member, said first cross-sectional area applied along a first seat length of said first mid-span seat; b. a bottom tension member connecting said second bottom cross-sectional tension zone interrupted by said second midspan seat.
 5. The joint according to claim 3 wherein said first midspan seat further comprises: a. a substantially rectilinear seat extending from a top edge of said first load-carrying member to about a central axis of said first load-carrying member; b. said rectilinear seat further comprising a width substantially great enough to accept a cross-sectional width of said second load-carrying member.
 6. The joint according to claim 3 wherein said second midspan seat further comprises: a. a substantially rectilinear seat extending from the bottom edge of said second load-carrying member to about a central axis of said second load-carrying member; b. said second rectilinear seat further comprising a width substantially great enough to accept a cross-sectional width of said first load-carrying member.
 7. The joint according to claim 1 wherein said first midspan seat further comprises: a first transversely aligned through port perpendicular to a longitudinal lengthwise axis of said first load-carrying member, said transversely aligned through port ranged to receive said second load-carrying member comprising a second load-carrying member cross-sectional area.
 8. The joint according to claim 7 wherein said first transversely aligned through port further comprises: a circular cross-section to receive said second load-carrying member comprising a circular cross-section.
 9. The joint according to claim 7 wherein said first transversely aligned through port further comprises: a rectilinear cross-section to receive said second load-carrying member comprising a rectilinear cross-section.
 10. A manhole installation and repair assembly, said assembly comprising: a. a first load-carrying member comprising a longitudinal length to span over an excavation region encompassing a manhole cone, said first load-carrying member further comprising a first midspan seat arranged substantially at a first midspan location of said first load-carrying member; b. a second-load carrying member comprising a transverse length to span over said excavated region, said second load-carrying member further comprising a second midspan seat arranged substantially at a second midspan location of said second load-carrying member; c. said first midspan seat arranged to receive said second midspan seat and form a crossmember joint enabling said first load-carrying member and said second load-carrying member to be arranged within a substantially horizontal plane; d. said first load-carrying member further comprising two first ground engaging locations at either end of said first load-carrying member; e. said second load-carrying member further comprising two second ground engaging locations at either end of said second load-carrying member; f. said first load-carrying member further comprising two adjustable manhole retainer elements to operably engage at diametrically opposed locations a manhole ring; g. said second-load carrying member further comprising two adjustable manhole retainer elements to operably engage at diametrically opposed locations a manhole ring; h. an inflatable form liner comprising an outer wall to maintain a seal between an inside face of a proposed manhole cone extension wall above a top edge of said manhole cone and a bottom edge of said manhole ring.
 11. The assembly according to claim 10 wherein said first load-carrying member further comprises one or more of the following materials: aluminum, steel, carbon fiber, wood, plastic.
 12. The assembly according to claim 10 wherein said second load-carrying member further comprises one or more of the following materials: aluminum, steel, carbon fiber, wood, plastic.
 13. The assembly according to claim 10 wherein said assembly further comprises: a. said first load-carrying member comprising a first rectilinear cross-section; b. said second load-carrying member further comprises a second rectilinear cross-section.
 14. The assembly according to claim 10 wherein said assembly further comprises: a. said first load-carrying member comprising a first circular tube steel cross-section; b. said second load-ember further comprising a second circular tube steel cross-section.
 15. The assembly according to claim 10 wherein said adjustable manhole retainer element further comprises: sliding sleeves configured to attach to an outside face of said manhole ring.
 16. The assembly according to claim 10 wherein said assembly further comprises: a. said manhole ring holding a manhole cover, said manhole ring and manhole cover maintained in a suspended position by said manhole retainer elements below said first load-carrying member and said second load-carrying member, b. said first load-carrying member and said second load-carrying member maintaining a manhole grade aligned with a roadway grade.
 17. The assembly according to claim 10 wherein said inflatable form liner further comprises: a. an adjustable conically shaped plastic form liner wall; b. an inflatable bladder configured in a substantially circumferential doughnut arrangement.
 18. The assembly according to claim 10 wherein said inflatable form liner further comprises: a flat tube inflatable bladder comprising an outer wall and an inner wall, said outer wall forming a seal between said manhole ring and said manhole cone.
 19. The assembly according to claim 18 wherein said flat tube inflatable bladder further comprises: said outer wall comprising a puncture resistant material.
 20. The assembly according to claim 10 wherein said cross member joint further comprises: said first load-carrying member and said second-carrying member resisting a maximum midspan moment provided by said carried load and applied at the crossmember joint.
 21. The assembly according to claim 10 wherein said cross member joint further comprises: a. said first load-carrying member comprising a first top cross sectional compression zone, said first top cross sectional compression zone interrupted by said first midspan seat; b. said second load carrying member comprising a second bottom cross sectional tension zone, said second bottom cross sectional tension zone interrupted by said second midspan seat; c. said second midspan seat of said second load-carrying member further comprising a second top compression zone to transfer a first compression force in said first load-carrying member across said first midspan seat; d. said first midspan seat of said first load carrying member further comprising a first bottom tension zone to transfer a second tension force in said second load carrying member across said second midspan seat.
 22. The assembly according to claim 21 wherein said first bottom tension zone further comprises: a. a first cross-sectional area of said first load carrying member, said first cross-sectional area applied along a first seat length of said first mid-span seat; b. a bottom tension member connecting said second bottom cross-sectional tension zone interrupted by said second midspan seat.
 23. The assembly according to claim 21 wherein said first midspan seat further comprises: a. a substantially rectilinear seat extending from a top edge of said first load-carrying member to about a central axis of said first load-carrying member; b. said rectilinear seat further comprising a width substantially great enough to accept a cross-sectional width of said second load-carrying member.
 24. The assembly according to claim 21 wherein said second midspan seat further comprises: a. a substantially rectilinear seat extending from the bottom edge of said second load-carrying member to about a central axis of said second load-carrying member; b. said second rectilinear seat further comprising a width substantially great enough to accept a cross-sectional width of said first load-carrying member.
 25. The assembly according to claim 10 wherein said first midspan seat further comprises: a. a first transversely aligned through port perpendicular to a longitudinal lengthwise axis of said first load-carrying member, said transversely aligned through port ranged to receive said second load-carrying member comprising a second load-carrying member cross-sectional area.
 26. The joint according to claim 25 wherein said first transversely aligned through port further comprises: a circular cross-section to receive said second load-carrying member comprising a circular cross-section.
 27. The joint according to claim 25 wherein said first transversely aligned through port further comprises: a rectilinear cross-section to receive said second load-carrying member comprising a rectilinear cross-section.
 28. An installation method of a manhole cover, said method comprising: b. maintaining an excavation region encompassing a manhole cone; c. assembling a first load-carrying member and a second load-carrying member by: i. seating a second midspan seat of said second load-carrying member with a first midspan seat of said first load-carrying member to form a midspan crossmember joint; d. attaching said first and second load-carrying members to a manhole iron rim; e. placing said assembly at a roadway grade; f. positioning said manhole iron rim above said manhole cone; g. installing an inflatable form liner between said manhole iron rim and said manhole cone; h. filling said excavation region with concrete; i. removing said first load-carrying member and said second load-carrying member from said manhole iron rim; j. curing said concrete; k. laying asphalt above said concrete at said roadway grade.
 29. An assembly for installation of a manhole cover, said assembly comprising: a. means for excavating an excavation region encompassing a manhole cone; b. means for assembling a first load-carrying member and a second load-carrying member said means comprising: i. seating a second midspan seat of said second load-carrying member with a first midspan seat of said first load-carrying member to form a midspan crossmember joint; c. means for attaching said first and second load-carrying members to a manhole iron rim; d. means for placing said assembly at a roadway grade; e. means for positioning said manhole iron rim above said manhole cone; f. means for installing an inflatable form liner between said manhole iron rim and said manhole cone; g. means for filling said excavation region with concrete; h. means for removing said first load-carrying member and said second load-carrying member from said manhole iron rim; i. means for curing said concrete; j. means for laying asphalt above said concrete at said roadway grade. 